misc: delete gh workflow

.github/workflows/dockerimage.yml

-name: Docker Image CI
-
-on:
-  push:
-    branches:
-      - master2
-
-jobs:
-
-  build:
- 
-    runs-on: ubuntu-latest
-    
-    timeout-minutes: 30
- 
-    steps:
-    - uses: actions/checkout@v1
-    - name: Build the Docker image
-      run: docker build . --file dev/build/Dockerfile -t requarks/wiki:dev
-      
-    - name: Login to Docker Hub
-      run: docker login -u ${{ secrets.DOCKER_USERNAME }} -p ${{ secrets.DOCKER_PASSWORD }}
-      
-    - name: Push to Docker Hub
-      run: docker push requarks/wiki:dev
-      
-    - name: Logout from Docker Hub
-      run: docker logout